Catalytic re-forming of hydrocarbons



' silica, etc., having deposited thereon a relatively Patented Sept. 1942 n uNlrsD STATES PATENT oFFlcEf l H.. z,z95,197 n cATALmc 1in-Fourmis or mnocAnBoNs Ware Appucaum anni 2z, 1949, serial No. 999,955

4.01am. (ci, 19e- 52) This invention relates to a process for improving the antiknock value of straight run and cracked hydrocarbon distillates boiling substantially within the motor fuel range to produce substantially olefin-.free gasoline of high antiknock value and improved susceptibility to tetraethyl lead.

The reforming of straight run naphthas by non-fcatalytic methods has been carried out and various catalytic materials have been suggested to assist in improving the antiknock value thereof. In many instances these processes yield oleincontaining motor fuels which are of great utility in automobile engines butwhich because ofthe olen content are undesirable as aviation fuels and which likewise have relativelylow susceptibility to octane number increases bythe addition thereto of tetraethyl lead.

In one specific embodiment the present inven tion is a process for improving the antiknock value of straight runand cracked distillates of motor' lfuel boiling range' which comprises contacting a similar to that usednfthe primary reaction zone at a temperature oi. approximately 45041550" C. and a pressure of approximately 100-2000 pounds per square inch to produce a substantially oleiinfre'e motor iuel of improved antiknock value, iractionating the reaction products, recovering the gasoline, recovering VaQhydrogeincontaining fram,

tion :from the gaseous portion of said reaction products and, returning a portion ofsaid fraction to the primary reaction zone. y

The catalytic agents useful in this process normally comprise relativelyY inert carriers such as activated alumina, titania.. magnesia, thoria,

chromia, alumina-molybdena, etc., are particularly eiective and eilicientA composites. These catalysts may be prepared by impregrlating,` the carrier `with a solution of thecompounds` to be 6 used, such as the nitrate followed by calcining the mixture at a temperature 'of approximately 500 C. or higher. In another Variationen acid such as chromic acid may be mixed with the carrier such as for examplealumina, vand .the mixture heated to form the catalytic mass. Normally these materials are used in the form of granules or shaped forms such as pelletspspheres, etc..

such shapes priork to the calcination step.

In another variation a hydrate of the carrier such as aluminum hydrate, may be formed into shapes and these impregnated withla solution oi the compound to -be added, the mixture finally being calcined to produce a finished catalyst.

The catalyst mayalso compriseamixture of the composites described with varying percentages of catalysts of the silica-alumina, silica-zirconia, silica-alumina-zirconia, etc., type.. These in general are prepared by the separate orsimultaneous precipitation of the components followed .by 'ap. propriete washing, drying and calcining operations. Alkali metalions are preferably removed substantially completely during the course'lof preparation. 'l

It is within-the scope of the invention to` use catalysts of different composition in thyarious steps of the process. Thusfor example, a composite of the alumlna-chromia, alumina-molyb-4 dena, etc type-may be used in the primary step :for the initial treatmentv of the A straight run naphtha or gasoline. In the second step, wherel in the mixture of reaction products tromthe prif @mary step with cracked gasolineis treated, the same or similar catalyst may be used, or a mixed y' composite such as that described in the lforegoing paragraph maybe used.

' It should be understood thatv the various cata-#r lytic agents .described are'inot necessarily exactly 40 equivalent in their action or eiii-ciency in promoting the'desiredreactiona v `The invention maybe better understood by .vreferenceto the accompanying drawing whichis purely diagrammatic and illustrates one embodiment of the process, but which should not be conapparatus or strued as limiting it to the exact conditions shown therein.

approximately 245 C., is introduced through' line v if, valve 2, pump 3 and valve 4. It is mixed with hydrogen or a hydrogen-containing gas from line 5 5, valve 6, pump 1 and valve 8 gand the mixture and the impregnated powder may be formed into `A straight run hydrocarbon oil such as naphtha` :boiling substantially 'within the gasoline range or Y slightlyv above thegasoline range, for example, a

` traction having an end point `of not more than Here it is heated to a temperature actions. The temperature maintained herein is of the order of 50o-650 C. and a pressure substantially atmospheric or slightly superatmospheric, say of the order of 50-100 pounds per square inch. When operating under the conditions described using catalysts of the character described, the gaseous hydrogen content offthe gas fraction of the reaction products from the primary reaction zone is substantially increased.

The reaction products pass through line I5, cooler I6, valve I1 to line I8 wherein they mingle withcracked gasoline entering from line I9 and valve 20. The mixture is pumped by pump ZI through valve 22 to coil 23 which is disposed in heater 24. Here the temperature is increased and the mixture is passed through line 25 and valve 26 to reaction zone 211 wherein a temperature of approximately 450-550" C. and a pressure s of approximately 10042000 pounds per square inch or higher is maintained. The catalytic agent used at this point may be of the same class as that used in reaction zone I4 but need not be identical with it. The reaction products pass through line 28 and valve 29 to fractionator 30. A residual oil boiling above the gasoline range, of which a small quantity may be formed, is

withdrawn through line 3| and valve 32. 'Gasoline and gas pass through line 33 and valve 34 to condenser 35 andthence through line 36 and valve 31 tov receiver 38, The gasoline may be withdrawn through line 39 and valve-40. The gasoline is substantially olefin-free and of low sulfurcontent and may be used as an aviation fuel or for high antiknock motor fuel wherein a high degree of susceptibility to tetraethyl lead is desired." The gaseous reaction products together with hydrogen are passed through line v and low boiling hydrocarbons such as methane,

ethane, etc., which is recovered is removed through line 50 and valve 5I, joining with line 50 and thus being returned to the reforming system.

The catalytic agents employed in both reaction zones may gradually accumulatel carbonaceous or hydrocarbonaceous deposits which mask the catalytic activity of the composites and necessitate intermittent reactivation. This is usually accomplished by treatment with an oxygen containing gas at a temperature in the range of approximately 45o-'100 C. which may or lmay not be followed by a brief treatment with hydrogen prior to resuming processing. The intervals of reactivation vary widely with the conditions and catalysts used and may be from the order of an hour or so to a matter of several hours or even f days, Furthermore, the time between reactivamake the reactivation more convenient the reactors in each zone areusually supplied in duplicate, one being used in the process cycle while the other is being reactivated. It is, of course,4 ,possible to interrupt the processing period at intervals to accomplish the reviviiication. Al-Y though the lines -and equipment for reactivation v .consumption of hydrogen which is a costly it'em in many processes wherein cracked gasolines are converted to olefin-free fuels. Moreover, the hydrogen acts to prevent undue loss of catalytic activity and prevents carbon formation to a large extent. This results in an overall saving in operating costs and a reduction in material losses.v

Furthermore, the overall antiknock properties of the final treated gasoline are greatly improved by the presentmoperation.

The following example is given to illustrate. the usefulness and practicability of the process but should not be construed as limiting it to the exact conditionsor catalysts used therein.

A Mid-Continent naphtha having an octane number of Aapproximately 33 and a boiling range of approximately 90-2l0 C.'is mixed with approximately 43,000 cubic Ifeet of hydrogen per barrel of naphtha and passed over a catalyst consisting of approximately 88% alumina and 8% chromia at a. temperature of 550 C, and a pressure substantially atmospheric. The reaction products are cooled and mixed with a Mid- Continent ,cracked gasoline having a 210 C. end.

' point, in a ratio of approximately 36 gallons of tions may be diiferent in the different zones. `To

cracked gasoline per 42 gallon barrel of the original naphtha charged. 'I'he cracked gasoline had an octane number of L80, The total product recovered may amount to 88 volume per cent of the original charge having an octane number of 78, a bromine number of 7, water-white colorand a sulfur content of 0.01%. The hydrogen recovered amounts to 43,100 cubic feet and this may be recycled tothe first step.

The gasoline recovered is suitable for use in aviation blends, or could be used as a high antiknock motor fuel directly, or could be blended with other fuels whereby the susceptibility to tetraethyl lead may be increased. The octane number of the fuel with 3 cc. of tetraethyl lead is- 89.

We claim as our invention:

l. Aprocess for reforming hydrocarbon oil of substantially gasoline boiling range which comprises mixing a straight run oil withhydrogen, subjecting the mixture to catalytic reforming agent at a ltemperature within the range of 500- 650 C. and a pressure within the range of substantially atmospheric to pounds'per square inch, mixing resultant reaction products, including hydrogen, with a cracked hydrocarbon distillate of substantially gasoline boiling range,

subjecting the resultant mixture to catalytic reforming at a temperature within the range of approximately 45o-550 C. and a' pressure within the range of approxlmately'l00-2000 pounds per square inch, fractionating resultant reaction products into gas and gasoline, recovering the gasoline,A separating a hydrogen-containing fraction from the gases and returningand mixing said fraction with said straight run oil.

2. A process for reforming hydrocarbon oil of substantially gasoline boilingA range which comprises mixing -wa straight run naphtha with. a hydrogen-containing gas, contacting the mixture` with a catalytic composite consisting of a relatively inert carrier having deposited thereon a minor portion of an Aoxide of an element selected. from the group consisting of an element appear- V ing in the left-hand column of theth, 5th and 6th groups of the periodic table, at a temperature within the range of approximately 50G-650 C.'

and a pressure within the range of approximately atmospheric to 100 pounds per square inch, mixing the reaction products with a cracked hydrocarbon distillate of substantially gasoline boiling range, and contacting the mixture with acatalyst of the characterhereinbefore described at perature in the approximate range of 50G-651)y a temperature within the range of approximately l.

45o-550 C. and a pressure within the range of approximately 100-2000 pounds per square inch.

3. A process for producing anti-knock gasolinev of relatively low olen content which comprises catalytically reforming straight run petroleum distillate containing gasoline fractions in the presence of a hydrogen-containing gas at a ltem- C., thereby forming a reaction product containin'g a gaseous lfraction of increased hydrogen content, commingling cracked gasoline withsaid product and subjecting the resultant mixture Ato 'catalytic reforming at 'a temperature in-the approximate range of 450.-550 C. andunder'super-` atmospheric pressure.

4. A process for producing 'anti-knock .gasoline of relatively low olen content whichcomprises catalytically reforming straight run petroleum distillate containing gasoline fractions inl 'the presence of a hydrogen-containing gas at a temperature in the approximate range of 500- 650 C., thereby forming a reaction product containing a gaseous fractionof` increased hydrogen content, commingling cracked gasoline with said product and subjecting the resultant mixture to catalytic reforming atv a temperature in` the approximate range of 450-'550 C. and under superatmospheric pressure -in-.the approximate range of 100-2000 lbs. perY square inch.

I WAYNE L. BENEDICT.

` WILLIAM 'J'. MA'I'I-'OX.- 

